Method and device for forming files of sheets consisting of one or more sheets

ABSTRACT

In a method and a device for forming groups of sheets consisting of one or of a plurality of sheets, a predetermined number of sheets is first supplied to a first position in a collecting station so as to form a first group of sheets. As soon as the first group of sheets has been formed, it is moved from the first position to a second position in the collecting station, and then a predetermined number of sheets is moved to the first position in the collecting station so as to form a second group of sheets.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method and a device for forming groups of sheets consisting of one or of a plurality of sheets.

[0003] 2. Description of the Related Art

[0004] In the prior art, paper handling systems are known in which e.g. 2-up printed sheets are supplied to a cutter, separated from one another, and then placed ready for further processing by a subsequent machine. For this purpose, the 2-up printed sheets are placed one on top of the other by means of suitable machines, such as a merger, and, in this condition, they are applied to subsequent paper handling machines for further processing. Instead of the 2-up printed sheets, which are made available via a cutter, individual sheets are also supplied by means of a sheet applicator to subsequent paper handling machines, the sheets being placed ready in the sheet applicator e.g. in the form of a stack.

[0005] For further processing in the subsequent machines the sheets provided in this way, these subsequent machines take over one or a plurality of such waiting sheets, a collecting station being arranged prior to these machines; in this collecting station individual groups of sheets comprising one or a plurality of sheets are formed making use of the sheets which have been placed ready. The groups of sheets formed in the collecting station are, when the respective group of sheets has been finished, transferred to the subsequent machines, e.g. a folder or an enveloping unit.

[0006] The clock cycle with which individual sheets are placed ready by the cutter or the sheet applicator is faster than the clock cycle of the subsequent machines, i.e. the enveloping unit or the folder. By way of example, an enveloping unit is assumed, which receives sheets made available by a cutter. Such a cutter is able to carry out e.g. 1,000 cutting operations within a predetermined period of time, whereas the enveloping unit can carry out only 100 enveloping operations. This has the effect that, in a first case, in which the enveloping unit processes only single sheets, the cutter will be stopped at certain intervals, since it would provide too many sheets, whereas, in a second case, in which the enveloping unit envelops fifteen sheets at a time, the enveloping unit will have to be stopped at certain intervals, since the cutter is not able to provide a sufficient number of sheets.

[0007] The prior art discloses single-compartment collecting devices or collecting stations in the case of which sheets can be supplied at a high speed. When a stack of sheets formed or a group of sheets formed is being discharged, the discharge speed must, however, be reduced, since large stacks cannot be transported at such a high speed. Also a subsequent processing device, e.g. a collecting folder, reduces the maximum discharge speed. This has the effect that the collecting station is not able to collect new sheets until the preceding group has left the collecting area and until the stop associated with the collecting station has been closed again.

[0008] This known collecting station is disadvantageous insofar as it causes a reduction in the performance of the overall system, especially in the case of small collection amounts and fast precursors, such as sheet applicators or cutters. Another disadvantage is that the gap between the group which is being discharged and the subsequent sheet must be chosen large enough for guaranteeing a reliable function of the stop rake in the case of the largest collection amount and in the case of mechanical deviations occurring when the device is in operation. This has the effect that paper, i.e. a sheet, cannot be fed from the sheet feeding device (e.g. the cutter or the sheet applicator) until the collecting station has discharged the preceding group and is again ready to receive new sheets.

[0009] For example, when a precursor feeds paper at 6 m/s and a collecting station discharges paper at 3 m/s, the cycle performance will be reduced up to 33% in the case of a two-sheet collection amount.

[0010] Making reference to FIGS. 6 to 8, examples of sheet handling systems known from the prior art will be described in detail hereinbelow; in so doing, the above-described problems will be defined more clearly on the basis of the following description.

[0011]FIG. 6A shows a sheet or paper handling system 600 including a cutter 602 which is followed by a stop point or buffer 604. After this stop point 604 a merger 606 is arranged, which is, in turn, followed by a stop point or buffer 608. At the outlet of the stop point 608, a collecting station 610 is arranged, which forms groups of sheets that are subsequently discharged to a folder 612. The arrows shown in the representation in FIG. 6A in the individual machines indicate a sheet or paper travelling direction P.

[0012] In the cutter 602 a paper web which has already been printed on is cut so as to obtain individual sheets which are then made available to the stop point 604. As can be seen in FIG. 6A, the individual sheets B are arranged in juxtaposition parallel to a central axis X of the machine when seen in the paper travelling direction P. The merger 606 causes the sheets which are present at the stop point 604 to be placed one on top of the other in such a way that they are superimposed and arranged centrally relative to the central axis X of the machine, when seen in the paper travelling direction P. From the merger 606 the combined sheets are transferred to the additional stop point 608, and from this stop point 608 the groups of sheets are then transferred to the collecting station 610 in which a group of sheets 614 comprising one or a plurality of sheets is formed. As soon as the desired number of sheets has been reached in the group of sheets, the group of sheets 614 is discharged from the collecting station 610 and supplied to the folder 612 in which the folding operation in question is carried out. Subsequently, further processing of the sheets takes place, as far as this is necessary.

[0013]FIG. 6B shows a flow diagram which shows the discharge times for two-sheet groups that are arranged out of alignment, the time being plotted along the x-axis in this diagram, and the respective discharge times of the individual machines of the system 600 being plotted along the y-axis, as can be seen from the respective reference numerals indicated along the y-axis. With regard to the merger, it should be pointed out that reference numeral 606R stands for the discharge times of a sheet which is arranged on the right-hand side of the merger inlet relative to the central X of the machine, and that reference numeral 606L stands for the discharge time of a sheet which is present at the inlet of the merger on the left-hand side of the central axis X of the machine.

[0014] For the flow diagram, it is additionally assumed that the cutter carries out 24,000 cuts, that the length of each stop point is 330 mm, and that the merger 606 discharges the individual sheets in a displaced mode.

[0015] The discharge times obtained for the individual machines are 150 ms for the cutter 602, 120 ms for the stop point 604, 145 ms for the merger for each sheet, 70 ms for the stop point 608 for each sheet, and 150 ms for the collecting station 610. In the example shown, the discharge times of the individual components do not change, as can be seen from the fact that the lines in the diagram of FIG. 6B are equal in length.

[0016] At the time instance t=0 ms, a group of sheets 614, which has already been fully formed, is just being discharged from the collecting station 610. At this time instance t=0 ms, one sheet is present at the stop point 610, two sheets are present at the stop point 604 and the next sheets, which are to be cut, are placed ready at the outlet of the cutter 602.

[0017] Time-displaced from the start of the discharge of the sheets from the collecting station 610, the combination of the sheets in the stop point 604, which are positioned at the inlet of the merger 606, is started at t=75 ms; at t=75 ms, the movement of the left-hand sheet, and, with a time shift of 25 ms, the movement of the right-hand sheet are started. In order to guarantee that the stop point 608 is able to accommodate the sheets discharged from the merger, discharge of the sheet which is present in this stop point 608 is started at t=125 ms; this takes 70 ms, so that, as can be seen, this sheet reaches the collecting station 610, when the preceding group has already left the collecting station. At the time instance t=25 ms, the left-hand sheet in the merger 606 has reached the stop point 608 and is also discharged to the collecting station 610 by this stop point 608, so that, at t=290 ms, two sheets will again be arranged in the collecting station 610. When the individual sheets have started passing through the merger 606, the stop point 604 is driven in a time-displaced mode so as to make the sheets which are present in this stop point 604 available at the inlet of the merger 606; this takes 120 ms. The cutter has already been started previously so as to guarantee that, after the discharge of the sheets from the stop point 604, additional sheets are supplied from the cutter 602. As can be seen from FIG. 6B, this cycle is then repeated. The cycle time is 295 ms, this corresponds to approx. 12,200 cycles per hour. The times indicated may vary due to tolerances and other mechanical deviations in the components.

[0018] In FIG. 7, another example is shown; FIG. 7A shows a further paper handling machine 700 comprising a sheet applicator 702, a shingling belt 704, a stop point 706 and a collecting station 708, these components extending one after the other along a central axis X of the machine when seen in the paper travelling direction P. As can be seen from FIG. 7A, individual sheets are removed by the sheet applicator 702 and made available to the shingling belt 704 so that a plurality of sheets is arranged in a shingled mode of arrangement, as can be seen in FIG. 7A. From the shingling belt individual sheets are supplied to the stop point 706 from which these sheets are supplied to the collecting station 708 so as to form a group of sheets 710 comprising one or a plurality of sheets.

[0019]FIG. 7B shows a flow diagram in which the discharge times of the shingling means 704, the stop point 706 and the collecting station 708 are shown, the time t being plotted along the x-axis and the individual components of the sheet handling system 700 being plotted along the y-axis.

[0020] At the time instance t=0 ms, the discharge of a group of sheets 710, which is present in the collecting station 708, is started; this takes 150 ms. At this time instance, a sheet is already present in the stop point 706 and a respective number of sheets is present in the means 704. A short time before the group of sheets has fully been discharged from the collecting station 708, discharge of a sheet from the stop point 706 and transfer of the sheet, which constitutes the leading sheet in the paper travelling direction, from the shingling means 704 to the stop point 706 are simultaneously started at t=125 ms. The discharge of the sheet from the stop point 706 take 75 ms and the discharge of a sheet from the means 704 to the stop point 706 takes 100 ms. In order to guarantee that a two-sheet group is formed again, when the preceding group has been discharged from the collecting station 708, the sheet discharged from the shingling means 704 is, when it has reached the stop point 706, re-discharged from this stop point 706; this is done at a higher speed so that the time amounts to 65 ms. The times indicated may vary due to tolerances and other mechanical deviations in the components.

[0021] It follows that, at the end of the clock cycle, which takes 300 ms, two sheets are again present in the collecting station 708. In order to guarantee that also the stop point 706 contains a sheet once more, a further sheet is moved, in a time-displaced mode (100 ms), from the means 704 towards the stop point; this sheet arrives at the stop point, when the sheet which was previously present at this stop point has already been transferred to the collecting station, as can be seen from FIG. 7B at 704.

[0022] In FIG. 8, the gross cycle performances of the devices described on the basis of FIGS. 6 and 7 are summarized in tables, depending on the number of printed forms; FIG. 8A shows the gross cycle performance for the system described on the basis of FIG. 6, and FIG. 8B shows the gross cycle performance for the system described on the basis of FIG. 7.

[0023] In FIG. 8A, it is indicated in the column “PF group” (printed form group) that this printed form group is either arranged in pairs, in a displaced mode or mixed 1:1. In the case of an arrangement in pairs, the printed forms are arranged such that they are transferred from the cutter 602 to the stop point 604 in juxtaposition, i.e. sheets of a group of sheets are always arranged in respective pairs in juxtaposition. The “displaced arrangement” means that sheets which are associated with individual groups of sheets are not arranged in respective pairs in juxtaposition, but are arranged in the sheet travelling direction successively one after the other, i.e. whereas one sheet of a group of sheets is already arranged in the stop point 604, the preceding sheet is still located in the cutter 602. With respect to the “mixed arrangement” reference is made to the fact that this mode of arrangement expresses that 50% of the printed forms are arranged in a displaced mode and 50% of the printed forms are arranged in pairs. The two columns on the right-hand side indicate how many envelopes per hour or printed forms per hour can be processed, depending on the number of printed forms and the arrangement of the individual sheets.

[0024]FIG. 8B indicates the gross cycle performance per hour for the system described on the basis of FIG. 7 for different numbers of printed forms depending on the envelopes and printed forms processed. A grouping of the printed forms of the type effected in FIG. 8A does not take place, since the individual sheets are not placed ready in juxtaposition.

[0025] As can clearly be seen from the above explanation, the problem underlying the known devices is to be seen in the fact that the collecting station is not able to collect new sheets until the preceding group has left the collecting area. The suggested solutions, i.e. that the collecting station should be implemented such that it comprises a plurality of reception areas or collection areas between which a change-over is carried out, is disadvantageous in view of the increased mechanical outlay, the increased investment in control technology and the higher costs.

[0026] In the prior art solutions are already known, which avoid the necessity of stopping individual machines by arranging a stop point between the cutter and the subsequent machines, or by providing a collecting station with a buffer or stop-point means so as to permit a continuous operation.

[0027] In one case, the device in question is so conceived that sheets which have been placed ready are collected in a buffer and that, when a predetermined number of sheets has been reached, i.e. when a group of sheets has been formed, switching over to e.g. a second buffer plane is effected so that the sheets contained in the first buffer plane can be advanced for further processing, whereas sheets discharged by the cutter are simultaneously introduced in the second buffer. Such a device is described e.g. in U.S. Pat. No. 5,083,769.

[0028] A further solution is so conceived that the sheets which have been placed ready are deposited in a shingled mode in a single buffer; for forming groups of sheets, the shingled stream is advanced by a predetermined distance which corresponds to the number of sheets in the group of sheets to be formed, this number of sheets being then discharged. Such a solution is described in DE 199 40 405 A and in DE1 99 40 406 A.

[0029] The above described devices are disadvantageous insofar as they operate with a plurality of buffer areas or depositing areas; this leads to an increased mechanical outlay and a higher investment in control technology and this will, moreover, result in higher costs.

[0030] DE 4333575 A1 describes a method and a device for forming and displacing stacks of printed sheets. The sheets are advanced individually and superimposed in a shingled mode of arrangement in such a way that a subsequent sheet comes to rest below the preceding sheet in a displaced mode of arrangement. The stack is formed in that the shingled sheets knock against a stop. In order to lose little time when a finished stack of sheets is being displaced, a gap is formed between the last sheet belonging to the stack in question and the following sheet. As soon as the last sheet has reached the stacking position, the stop is moved away so that the stack will be moved away from the sheet conveyor. Subsequently, the stop is moved back to its stopping position and the next stack is formed.

SUMMARY OF THE INVENTION

[0031] It is the object of the present invention to provide an improved method and an improved device for forming groups of sheets, this method and device necessitating the reception of new sheets already before the preceding group has completely left the collecting device or collecting station, without any necessity of providing additional collecting areas.

[0032] The present invention is a method of forming groups of sheets consisting of one or of a plurality of sheets, the method having the follwing steps:

[0033] (a) supplying a predetermined number of sheets to a first position in a sheet feeding plane in a collecting station so as to form the first group of sheets;

[0034] (b) when the first group of sheets has been formed, moving the first group of sheets from said first position in the sheet feeding plane in the collecting station to a second position outside of the sheet feeding plane in the collecting station, and discharging the first group of sheets from the collecting station; and

[0035] (c) supplying a predetermined number of sheets to said first position in the sheet feeding plane in said collecting station so as to form a second group of sheets while the first group of sheets is being discharged from the collecting station.

[0036] The present invention is a device for forming groups of sheets consisting of one or of a plurality of sheets, the device having

[0037] a stationary collecting support for receiving thereon a predetermined number of sheets of a group of sheets;

[0038] a movable lifting means which moves a group of sheets accommodated on the collecting support from said collecting support to a further position; and

[0039] a control means which causes the collecting support to receive thereon a predetermined number of sheets of a first group of sheets, which causes the lifting means to move said first group of sheets to said further position ), and which causes the collecting support to receive thereon sheets of a second group of sheets.

[0040] The present invention is a device for forming groups of sheets consisting of one or of a plurality of sheets, the device having

[0041] a collecting means comprising a least two collecting compartments for receiving therein a predetermined number of sheets of a group of sheets;

[0042] a means for moving said collecting means so as to place one collecting compartment of the at least two collecting compartments ready for receiving sheets therein; and

[0043] a control means which causes a first collecting compartment to receive therein a predetermined number of sheets of a first group of sheets, which causes the first group of sheets to be discharged from the first collecting compartment, which causes said means to move the collecting means in this way, and which causes a second collecting compartment to be placed ready for the supply of sheets and to receive therein sheets of a second group of sheets while the first group of sheets is being discharged from the first collecting compartment.

[0044] According to a preferred embodiment of the present invention, the one or the plurality of sheets of a group of sheets is/are supplied to a collecting area. As soon as the predetermined number of sheets has been reached, the stack of sheets is moved in the direction of a discharge unit. When the discharge unit has been reached, the stack of sheets is vertically displaced so as to arrange it above the collecting area, i.e. the collecting area is cleared by lifting the finished stack of sheets so that sheets of the subsequent stack of sheets can be received in the collecting area substantially simultaneously with the discharge of the finished stack of sheets. The supply of additional sheets is made possible as soon as a sufficient distance has been established between the raised stack and the collecting area.

[0045] According to a further preferred embodiment of the present invention, the collecting station comprises a pivotable collecting means comprising at least two collecting compartments into which one or a plurality of sheets of a group of sheets are introduced. As soon as a predetermined number of sheets has been reached in a collecting compartment, the collecting means is pivoted so that another collecting compartment will be associated with the inlet of the collecting station, whereas the group of sheets formed will simultaneously be discharged from the collecting station. By pivoting the collecting means to the next collecting compartment, a sufficient distance between successive sheets is guaranteed for collecting in the collecting means so that the first group of sheets will reliably be discharged and the second group of sheets will reliably be introduced and moved into contact with a stop.

[0046] The advantage of the method according to the present invention and of the device according to the present invention are obvious, since it is now no longer necessary to wait until a group of sheets has fully been discharged from a collecting station. On the contrary, when a sufficient distance has been reached between the finished group of sheets and the collecting area, it will already be possible to receive new sheets. This leads to a substantial increase of the cycle performance of such a system and therefore to a substantial increase of the overall cycle performance of an overall paper handling system.

[0047] Another advantage of the method according to the present invention and of the device according to the present invention is that the complicated “double buffers” can be dispensed with so that the mechanical outlay, the investment in control technology and the costs will be reduced in comparison with such systems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] These and other objects and features of the present invention will become clear from the following description taken in conjunction with the accompanying drawing, in which:

[0049]FIGS. 1A to 1C show a schematic representation of a first embodiment of a device according to the present invention;

[0050]FIGS. 1 D to 1F show a schematic representation of a second embodiment of a device according to the present invention;

[0051]FIGS. 2A to 2D show a schematic representation of various positions of a lifting means of the type used in a device according to the present invention according to the first embodiment;

[0052]FIGS. 3A and 3B show a first paper handling system including the collecting device according to the present invention, and a flow diagram;

[0053]FIGS. 4A and 4B show a second example of a sheet handling system including the collecting device according to the present invention, and a flow diagram;

[0054]FIGS. 5A and 5B show comparisons of the gross cycle performances of the devices according to FIGS. 3 and 4 with sheet handling systems making use of conventional collecting devices;

[0055]FIGS. 6A and 6B show a first example of a conventional sheet handling system with a conventional collecting device, and a flow diagram;

[0056]FIGS. 7A and 7B show a second example of a conventional sheet handling system with a conventional collecting device, and a flow diagram; and

[0057]FIGS. 8A and 8B show, in tabular form, representations of the gross cycle performances of the paper handling systems of FIGS. 6 and 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] In the following, the method according to the present invention and the device according to the present invention will be described in general making reference to FIGS. 1 and 2, and, making reference to FIGS. 3 to 5, the use of the device according to the present invention in sheet handling systems and especially the improvement of the cycle times will be explained. The sheets described hereinbelow on the basis of FIG. 1 and FIG. 2 are designated generally by the reference symbol B and they stand for one or a plurality of sheets of a group of sheets.

[0059]FIG. 1A shows a schematic representation of a first embodiment of the device according to the present invention or rather of the collecting station according to the present invention which is designated generally by reference numeral 100. The collecting station 100 comprises a pair of input rolls 102 a and 102 b arranged at the inlet 104 of the collecting station 100 when seen in the sheet travelling direction P. The broken line 106 indicates the plane in which individual sheets enter the collecting station. A support 108 is arranged after the input rolls 102 a and 102 b when seen in the sheet travelling direction P; in FIG. 1A, this support 108 is concealed by a lifting means 110 and it is only indicated by a broken line for this reason. The sheets introduced in the collecting station are deposited on the support 108, which is arranged in the sheet feeding plane 106; it is evident that, in cases in which a plurality of sheets is to be received in the collecting station, these sheets will come to rest on the respective preceding sheet. In FIG. 1A, a sheet B is schematically shown.

[0060] The collecting station 100 additionally comprises a lifting means 110 provided with a lifting frame 112 whose exact structural design will be explained in detail hereinbelow with reference to FIG. 2. The lifting frame 112 is connected via a connecting rod 114 to a lifting drive 116 whose operation causes a displacement of the lifting frame 112 in the direction which is perpendicular to the sheet travelling direction P and which is indicated by the arrow V.

[0061] A pair of transport rolls 118 a and 118 b is arranged after the support 108, when seen in the sheet travelling direction P. The transport roll 118 a is arranged such that it movable in direction V and, via connecting rod 120, it is connected to a drive 122 causing a movement of the roll 118 a in direction V. The roll 118 b is arranged at a stationary position.

[0062] The collecting station 100 additionally comprises a stop 124 implemented as an L-shaped angular component in the case of the embodiment shown; it may, however, also be implemented in the form of a stop rake. The stop 124 is rotatably supported via a bearing 126, a respective movement of the stop 124 about the bearing 126 being effected by operating a drive 128 which moves a connecting rod 130 in direction V, whereby the stop 124 is tilted about the bearing 126 in a suitable manner.

[0063] A discharge unit 132 is arranged behind the stop 124, when seen in the sheet travelling direction P, and comprises two discharge rolls 134 a and 134 b. Discharge roll 134 a is pretensioned towards discharge roll 134 b via a spring 136 and arranged such that it is movable in direction V. Discharge roll 134 b is connected via a connecting rod 138 to a drive 140, which, when operated, causes a displacement of roll 134 b in direction V and, consequently, also a corresponding displacement of the roll 134 a in direction V.

[0064] In FIG. 1A the situation is shown in which a sheet B moves into the collecting station 100, and for the reflections following hereinbelow it will be assumed, for the sake of simplicity, that the group of sheets to be formed consists of only one sheet B. It is, however, apparent that the present invention is not limited to the formation of groups of sheets which consist of one sheet alone, but that the station 100 according to the present invention also accommodates a plurality of sheets of a single group.

[0065] In FIG. 1A, the sheet B has been moved onto the support 108 in the sheet feeding plane 106; the movement in the sheet travelling direction P was stopped by the stop 124.

[0066] In FIG. 1B, the situation is shown which occurs immediately after detection of the formation of a complete group of sheets. As soon as this has been detected, the drive 128 is actuated so as to move the connecting rod 130 in such a way that the stop 124 tilts around the bearing 26 downwards, as shown in FIG. 1B, so as to clear the path between the support plate 108 and the discharge unit 132. Simultaneously with the operation of the drive 128 also the drive 122 is operated so as to move the connecting rod 122 and thus the roll 118 a towards the roll 118 b in order to move sheet B in the direction of the discharge unit 132 by driving the transport rolls 118 a and 118 b. In FIG. 1B the situation is shown in which the sheet B has already arrived between the discharge rolls 134 a and 134 b.

[0067]FIG. 1C shows what happens when sheet B has arrived at the discharge rolls 134 of the discharge unit 132. As soon as this has been detected, the drives 116 and 140 are operated so as to move the lifting frame 112 and the discharge rolls 134 a, 134 b into a sheet discharge plane 142 which is vertically spaced from the sheet feeding plane 106 by a predetermined distance D. Simultaneously, the drive 122 is activated so as to move the transport roll 118 a vertically away from the transport roll 118 b, as can be seen in FIG. 1C, so that sheet B can be transported without hindrance. In addition, the drive 128 is actuated so as to cause, via the rod 130, the stop 124 to return to its closed position. As is only shown schematically in FIG. 1C, the lifting frame 112 includes a lifting frame support 144 on which sheet B rests during the lifting movement of the lifting frame 112, the support 108 remaining in its original position in a stationary manner. As soon as the situation shown in FIG. 1C has been accomplished, introduction of a new sheet B′ in the collecting station 100 can be started.

[0068] The above explanation shows clearly that the collecting station according to the present invention permits new sheets of a group of sheets to be introduced, although the preceding group has not yet left the collecting station.

[0069] In other words, the collecting station 100 makes it possible that, as soon as a group B has been collected, the stop 124 is opened, and the upper transport roll 118 a of the transport means, which is located in front of the stop 124, is pressed against the lower transport roll 118 b so that group B will be accelerated. Behind the stop 124, when seen in the sheet travelling direction P, the group B is taken over by the next transport roll 134 a/134 b of the discharge unit and, as soon as this has been done, this transport roll, the stop 124 and also the part of the group which is still located in the collecting area are lifted by the lifting means 110 to such an extent that the first sheet B′ of the next group can travel below the preceding group B up to the stop 124. The group to be discharged is now discharged over the stop 124. As soon as the group has been transported away from the collecting area, the lifting means is lowered again past the sheets that have already been collected, as will be described in detail hereinbelow making reference to FIG. 2.

[0070] Making reference to FIGS. 1D to 1F, a second embodiment of the device according to the present invention or rather of the collecting station according to the present invention will be explained in detail in the following. Similar elements or elements producing the same effect, which have already been explained on the basis of FIGS. 1A to 1C, are designated by the same reference numerals and will not be described once more.

[0071] The embodiment of the present invention described with reference to FIGS. 1D to 1F differs from the first embodiment insofar as the collecting station includes a pivotable collecting means 150 comprising at least a first collecting compartment 152 and a second collecting compartment 154. The first collecting compartment 152 and the second compartment 154 comprise an inlet 152 a and 154 a, respectively, and a common outlet 156. The inlets 152 a and 154 b are arranged adjacent the inlet 104, and the common outlet is arranged adjacent the transport rolls 118 a and 118 b. In view of this arrangement, the two collecting compartments 152 and 154 use the stop 124 in common. The collecting compartments 152 and 154 are separated by a separation plate 158 so that the two collecting compartments 152 and 154 are defined in the collecting means 150. The collecting means 150 as a whole is pivotably supported, the bearing (not shown) being arranged adjacent the common outlet 156 in such a way that, when the collecting means 150 moves in the direction of the arrows shown in FIG. 1D, a movement of the inlets 152 a, 154 a of the collecting compartments 152 and 154 towards the inlet 104 and away from the inlet 104 is made possible, the common outlet 156 remaining simultaneously at a position adjacent the transport rolls 118 a, 118 b without any change of position. In the case of the embodiment of the present invention shown on the basis of FIGS. 1D to 1F, the control 146 is effective so as to cause a suitable movement of the collecting means 150, depending on the groups of sheets to be formed, and of the other elements of the collecting station 100, as will be explained in detail hereinbelow.

[0072] Other than in the case of the embodiment shown in FIGS. 1A to 1C, where a group of sheets formed is vertically displaced, the group of sheets remains here, after having been formed, essentially in the sheet travelling plane 106 during the discharge operation, so that a vertical displacement of the discharge unit 132 is not necessary, which means that the height adjustment mechanisms of the discharge unit 132, which have been shown on the basis of FIGS. 1A to 1C, can be dispensed with in the present case.

[0073] In the following, the mode of operation of the device according to the second embodiment will be explained in detail. FIG. 1D shows a starting situation in which sheets are fed to the first collecting compartment 152 via the inlet 104 and the rolls 102 a and 102 b. In FIG. 1D only one sheet B is shown schematically so as to prevent the representation from becoming excessively complex. The sheet B is advanced in such a way that it moves against the stop 124 in the first collecting compartment 152. Additional sheets are introduced in the collecting compartment 152 until a desired number or an admissible number of sheets has been received therein. According to one embodiment, the inlet 104 is provided with a so-called sluice which permits the sheets to be arranged in the collecting compartments either in an ascending or descending mode in accordance with their arrival at the collecting station 100, i.e. the respective sheets are arranged either on top of the preceding sheet or below the preceding sheet.

[0074] As soon as the control means 146 detects that the desired number of sheets of the group of sheets has been formed in the collecting compartment 152, it causes the stop 124 to move downwards, as can be seen in FIG. 1E, by operating the motor 128 accordingly. Simultaneously, the transport rolls 118 a and 118 b are moved, by operating the motor 122, in such a way that they engage the group of sheets and move it in the direction of the discharge unit 132. Simultaneously with the movement of the group of sheets B in the direction of the discharge unit 132, the control means 146 causes a pivotal movement of the collecting means 150, as indicated by the arrow in FIG. 1E, so as to move the inlet 154 a of the second collecting compartment 154 in the direction of the inlet 104 of the collecting station 100. As soon as the inlet 154 a is in alignment with the inlet 104 of the collecting station 100, the control starts to supply sheets, which are associated with the second group of sheets, into the second collecting compartment 154. By pivoting the collecting means during the discharge of the first group of sheets and, if necessary, by an accelerated discharge of the first group of sheets in comparison with the supply of additional sheets, a sufficiently large distance is produced between the two groups of sheets so that the supply of additional sheets into the second collecting compartment 154 can already be started at a time at which the first group of sheets has not yet been discharged completely. As soon as the first group of sheets has been discharged completely, the stop 124 is returned to its closed position, as can be seen in FIG. 1F, and the sheets of the second group of sheets are received in the second collecting compartment 154.

[0075] The movement of the collecting compartment 150 is effected with the aid of a suitable means which is schematically shown in FIG. 1D and designated by reference numeral 160 and which can be implemented e.g. such that it is similar to the lifting means of the first embodiment.

[0076] The advantage of the present invention resides in the fact that the performance can be increased substantially and, in addition, a reliable function of the stop is obtained, the stop being subjected neither to any influence caused by the group size nor to any mechanical control processes nor to wear.

[0077] It follows that the present invention makes it possible that, while a collected group is being discharged, the collection of the next group can already be started, whereby the collection performance of the system can be increased substantially.

[0078] According to a preferred embodiment the collecting station 100 is implemented such that either individual sheets or two superimposed sheets can be collected in an ascending or descending mode. The feeding and discharge speeds, i.e. the speeds of the transport rolls 102 and 134, are freely programmable, so are the stop positions of the sheets. Control of the individual drives and transport rolls is effected by a control means 146 of the collecting station, which is shown schematically in FIG. 1. The control means 146 is able to manage and to buffer sheet information required for the processing, such as the number of sheets in a group of sheets and the like.

[0079] Making reference to FIG. 2, the functional principle of the lifting means 110 according to the first embodiment will be explained in detail in the following. In order to make things easier, only the lifting frame 112 is shown in FIG. 2.

[0080] As can be seen in FIG. 2A, the lifting frame 112 comprises a first side element 202 and a second side element 204, which are arranged in parallel in the sheet travelling direction P (in FIG. 2 the direction perpendicular to the sheet plane) and which have a substantially identical structural design and are vertically adjustable. Due to the combined effect of the movable side elements 202 and 204, a first reception area 206 and a second reception area 208 are formed in the lifting element 112. The first and second reception areas 206 and 208 are separated by a projection 202 a and 204 a, respectively, provided in the respective side elements. The upper reception area 206 is delimited by the projections 202 a and 204 a as well as by the covers 202 b and 204 b. Likewise, the lower reception area 208 is delimited by lower boundary elements 202 c and 204 c and by the projections 202 a an 204 a. FIG. 2 additionally shows the stationary support 108 which has already been described on the basis of FIG. 1. This support is arranged in a stationary manner, i.e. it does not change position.

[0081]FIG. 2A shows a situation corresponding to that according to FIG. 1A, viz. the situation in which a group of sheets B has been formed. When it has been detected that a group of sheets B has been formed, this group of sheets B is moved in the direction of the discharge unit (FIG. 1, 132), and, when it has reached the discharge unit, the lifting frame 112 is raised so as to arrive at the position shown in FIG. 2B. As can be seen in the figure, the lifting of the lifting frame 112 has the effect that the group of sheets B is moved on the projections 202 a and 204 a from the sheet feeding plane to the sheet discharge plane. As soon as the lifting frame 112 has reached the raised position, a further sheet B′ of a subsequent group of sheets can be received in the second reception area 208, as can be seen in FIG. 2B.

[0082] When the preceding group of sheets B has been discharged, the two side elements 202 and 204 are moved away from each other relative to the width direction of sheet B′ so that the position shown in FIG. 2C is obtained. Subsequently, the lifting frame is lowered, as can be seen in FIG. 2D, and the side elements are again moved towards each other so that the situation shown in FIG. 2A is obtained once more.

[0083] Making reference to FIGS. 3 to 5, examples of sheet handling systems will be described hereinbelow; these sheet handling systems use the collecting station according to the present invention and the method for forming groups of sheets according to the present invention.

[0084]FIG. 3A shows a first example of a sheet handling system 300 comprising a cutter 302, a first stop point or first buffer 304, a merger 306, a second stop point or second buffer 308, the collecting station 100 according to the present invention as well as a folder 310, which are arranged in succession in the sheet travelling direction P. A printed paper web is provided for the cutter 302; this printed paper web is cut by the cutter so as to obtain individual sheets B which are introduced in the first stop point 304 such that they are juxtaposed relative to the central axis X of the machine. From the first stop point 304, the parallel, juxtaposed sheets are supplied to the inlet of the merger 306, which aligns the two sheets relative to the central axis X of the machine such that they are superimposed, sheets present at the outlet of the merger being transferred to the second stop point 308; from this second stop point 308 they are supplied to the collecting means 100 according to the present invention. The collecting means 100 discharges the groups of sheets formed to the folder 310 for further processing.

[0085]FIG. 3B shows a flow diagram in which the time t is plotted along the x-axis and the individual components of the device 300 are plotted along the y-axis. The discharge times of the individual components are shown in the diagram.

[0086] At the time instance t=0 ms, the discharge of a group of sheets, which has already been formed, from the collecting station 100 is started; this takes 150 ms. Simultaneously, the movement of a sheet (reference numeral 306L), which is present at the left-hand side of the merger inlet with respect to the central axis X of the machine, through the merger is started; this takes 145 ms. The use of the collecting station 100 according to the present invention allows the supply of additional sheets already a short time after the start of the discharge of the formed group of sheets from the collecting station 100; in the case of the embodiment shown, this takes place at the time instance t=25 ms, and at this time instance (t=25 ms) the discharge of a sheet, which is present at the stop point 308, from this stop point 308 and the supply of this sheet to the collecting station 100 are started; this takes 70 ms. Simultaneously with the start of the discharge of a sheet from the stop point 308, the movement of a sheet, which is present at the right-hand side of the merger inlet with respect to the central axis X of the machine, through the merger is started; this takes 145 ms (reference numeral 306R).

[0087] Time-displaced from the above, the provision of the sheets, which are arranged at the stop point 304, at the inlet of the merger is started at t=50 ms; this takes 125 ms. Simultaneously, the provision of new, cut individual sheets for the stop point 304 by means of the cutter 302 is started; this takes 150 ms. As can additionally be seen, the discharge of the sheet, which has now been introduced in the stop point 308, from this stop point 308 and supply of this sheet to the station 100 are started at the time instance t=145 ms.

[0088] As can be seen from FIG. 3B, the cycle time is 215 ms in the case of this embodiment; this corresponds to approx. 16,740 cycles per hour. This means that, in comparison with the conventional system described on the basis of FIG. 6, the cycle time has been reduced by 80 ms.

[0089]FIG. 4A shows a further sheet handling system 400, comprising, in succession when seen in the paper travelling direction, a sheet applicator 402, a shingling belt 404, a stop point or buffer 406 and the collecting station 100 according to the present invention. The sheet applicator 402 discharges individual sheets to the shingling belt 404, which temporarily stores these sheets in a shingled mode of arrangement and discharges at the outlet thereof individual sheets to the stop point 406, which, in turn, supplies sheets to the collecting station 100 according to the present invention.

[0090]FIG. 4B shows a flow diagram with the discharge times of the individual components of the system 400, the time t being plotted along the x-axis and the individual components being plotted along the y-axis.

[0091] At the time instance t=0 ms, the discharge of a group of sheets, which has already been formed, from the collecting station 100 is started; this takes 150 ms. The use of the collecting station 100 according to the present invention allows for starting, at t=30 ms, the introduction of a new sheet from the stop point 406 into the collecting station 100 already a short time after the start of the discharge of the group from the collecting station 100; this takes 70 ms. Simultaneously, the movement of a further sheet from the shingling belt 404 into the stop point 406 is started; this takes 115 ms. As soon as this sheet has reached the stop point, it is discharged from this stop point to the collecting station 100 at a higher speed; this takes 65 ms. 100 ms after the discharge of the sheet from the shingling belt has been started, discharge of a further sheet from the shingling belt in the direction of the stop point 406 is started; this takes again 115 ms.

[0092] As can be seen from FIG. 4B, the use of the device according to the present invention results in a cycle time of 200 ms; this means that, in comparison with the prior art described on the basis of FIG. 7, the cycle time has been improved by 100 ms.

[0093]FIGS. 5A and 5B show, in the form of tables, the gross cycle performances that can be achieved by the present invention for different numbers of printed forms in a group, and, in addition, a comparison is made with the systems of FIGS. 6 and 7, which use a conventional collecting station.

[0094] As can be seen, a substantial increase in cycle performance is obtained the use of the collecting station according to the present invention and by the application of the method according to the present invention.

[0095] It is therefore clearly evident that, in comparison with systems and devices according to the prior art, the present invention provides clear advantages with regard to the cycle performance that can be obtained; this is achieved due to the fact that the collection of additional sheets for a subsequent group can already be started during the discharge of a finished group from the collecting station.

[0096] While illustrative and presently preferred embodiments of the invention have been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations. 

What is claimed is:
 1. A method of forming groups of sheets consisting of one or of a plurality of sheets, comprising: (a) supplying a predetermined number of sheets to a first position in a sheet feeding plane in a collecting station so as to form the first group of sheets; (b) when the first group of sheets has been formed, moving the first group of sheets from said first position in the sheet feeding plane in the collecting station to a second position outside of the sheet feeding plane in the collecting station, and discharging the first group of sheets from the collecting station; and (c) supplying a predetermined number of sheets to said first position in the sheet feeding plane in said collecting station so as to form a second group of sheets while the first group of sheets is being discharged from the collecting station.
 2. A method according to claim 1, wherein, in step (b), the first group is moved in a direction perpendicular to the sheet feeding direction into a sheet discharge plane.
 3. A method according to claim 1, wherein the first group is moved in the direction of a discharge unit of the collecting station.
 4. A method according to claim 1, wherein, in step (a), the sheets are moved against a stop in a sheet traveling direction.
 5. A method according to claim 4, wherein step (b) comprises the following steps: (b.1.) moving the stop to an open position; (b.2.) moving the formed group to a discharge unit; and (b.3.) when the discharge unit has been reached, moving said discharge unit and said first group in a direction perpendicular to the sheet traveling direction and moving the stop to a closed position.
 6. A method according to claim 5, wherein the supply of sheets of the second group begins when the stop has reached the closed position in step (b.3.).
 7. A method according to claim 1, wherein the collecting station comprises a collecting means including at least two collecting compartments, wherein, in step (a), at least one inlet of a first collecting compartment is located in the sheet feeding plane and the sheets are supplied to said first collecting compartment, wherein, in step (c), at least one inlet of a second collecting compartment is located in the sheet feeding plane and the sheets are supplied to said second collecting compartment, and wherein said step (b) comprises the following step: moving the collecting means in such a way that the second collecting compartment is available for a supply of sheets in step (c).
 8. A method according to claim 7, wherein the group of sheets and the collecting means are moved essentially simultaneously in step (b).
 9. A method according to claim 7, wherein the first group is moved in the direction of a discharge unit of the collecting station.
 10. A method according to claim 7, wherein, in step (a), the sheets are moved against a stop in a sheet travelling direction.
 11. A method according to claim 10, wherein step (b) comprises the following steps: moving the stop to an open position: moving the formed group to a discharge unit; and when the discharge unit has been reached, moving the collecting means in such a way that the second collecting compartment is available for the supply of sheets in step (c).
 12. A method according to claim 11, wherein the supply of sheets of the second group is started when the second collecting compartment is available for the supply of sheets, the stop being moved to a closed position when the first group has been discharged.
 13. A method according to claim 7, wherein the collecting station is supported such that an outlet of the first collecting compartment and of the second collecting compartment are located essentially in the sheet discharge plane.
 14. A device for forming groups of sheets consisting of one or of a plurality of sheets, comprising: a stationary collecting support for receiving thereon a predetermined number of sheets of a group of sheets; a movable lifting means which moves a group of sheets accommodated on the collecting support from said collecting support to a further position; and a control means which causes the collecting support to receive thereon a predetermined number of sheets of a first group of sheets, which causes the lifting means to move said first group of sheets to said further position ), and which causes the collecting support to receive thereon sheets of a second group of sheets.
 15. A device according to claim 14, wherein the lifting means moves the first group in a direction perpendicular to a direction in which sheets are supplied to the collecting support.
 16. A device according to claim 14, comprising a discharge unit, wherein the control means causes the discharge unit to discharge the first group while sheets of the second group are being supplied.
 17. A device according to claim 14, comprising a stop occupying a closed position so as to form groups of sheets on the collecting support and occupying an open position so as to move a group of sheets away from the collecting support.
 18. A device according to claim 14, wherein the lifting means is provided with first and second vertically adjustable side supports whose distance is adjustable in a direction transversely to the sheet travelling direction so as to be larger than or smaller than a width of a sheet of the group of sheets.
 19. A device for forming groups of sheets consisting of one or of a plurality of sheets, comprising: a collecting means comprising a least two collecting compartments for receiving therein a predetermined number of sheets of a group of sheets; a means for moving said collecting means so as to place one collecting compartment of the at least two collecting compartments ready for receiving sheets therein; and a control means which causes a first collecting compartment to receive therein a predetermined number of sheets of a first group of sheets, which causes the first group of sheets to be discharged from the first collecting compartment, which causes said means to move the collecting means in this way, and which causes a second collecting compartment to be placed ready for the supply of sheets and to receive therein sheets of a second group of sheets while the first group of sheets is being discharged from the first collecting compartment.
 20. A device according to claim 19, comprising a discharge unit, wherein the control means causes the discharge unit to discharge the first group during the supply of sheets of the second group.
 21. A device according to claim 19, comprising a stop which occupies a closed position so as to form groups of sheets in the collecting compartment and which occupies an open position so as to move a group of sheets out of said collecting compartment.
 22. A device according to claim 21, wherein the control means causes the stop to move to an open position, causes the formed group to move to a discharge unit, causes, when the discharge unit has been reached, a movement of the collecting means in such a way that the second collecting compartment is placed ready for the supply of sheets, and causes the first group to be discharged from the collecting station.
 23. A device according to claim 22, wherein the control means causes the supply of sheets of the second group, when the second collecting compartment has been placed ready for the supply of sheets, said control means causing a movement of the stop to a closed position when the first group has been discharged. 